1. Field of the Invention
The present invention relates to a bending device for various kinds of pipes of different shapes each having a comparatively small diameter in the order of not more than about 20 m/m and a large thickness and which forms an oil, air or fuel supply path generally employed by an automobile or various kinds of machines and equipment.
2. Description of the Prior Art
Conventionally, it has been usual that a thick steel pipe is used as a fuel injection pipe of a diesel engine so as to withstand a high pressure. This pipe is provided with a connecting head for establishing its connection to the mating member and a clamping nut is fitted on the connecting head. Further, it is installed in a comparatively narrow space within the engine room as it is bent in a three-dimensional complicated form with respect to the fuel injection device. However, this type of pipe has a bent portion at a short distance from each end thereof and a nut is loosely fitted thereon so that a problem arises that it cannot be smoothly bent by a general automatic pipe bender which bends a tube at a plurality of portions in sequence in such a manner that a part of the pipe is fed between a stationary bending die and a rotary die while one end of the pipe is held clamped and the rotary die is rotated in a predetermined angle range in response to the movement of the pipe.
To meet the above difficulty, there has been provided, as a bending device, a unit bending jig 20 as shown in FIG. 5 which comprises a base 21 fixed with a bending die 22 of a shape corresponding to the desired bending shape and a stop wall 23 and a lever 25 attached with a die 24 and rotatable about the axis of the bending die 22. Where necessary, a plurality of such units may be prepared according to the number of bending steps so that the material pipe set on the base for each step of bending is bent at a plurality of portions in sequence by manually rotating the handle of the unit.
However, in the case of such a prior art device, the unit bending jig has generally been large-sized and of a heavy weight so that when the pipe is bent at each bending step or a tube having a different shape is bent, the bending unit must be replaced with another unit resulting in requiring much time and moreover, much labor is required for manual bending of the pipe resulting in lowering the productivity.